Arming switch



May 2, l1961 w. G. MEscHlNo ErAL 2,982,213

ARMING SWITCH Filed March 28, 195e vmw/DX, W u VFW.u am mmw m QF fw mE VW United States Patent O ARMING SWITCH William G. Meschino, Elmsford, and Rene Perdreaux, Jr.,

lrooklyn, N .Y., assignors to the United States of Amerrca as represented by the Secretary of the Army Filed Mar. 28, 1958, Ser. No. 725,474

4 Claims. (Cl. 102-70.2)

This invention is directed to an arming switch for use in an electrically detonated fuze.

An important consideration in the use of fuzed projectiles is the necessity for maintaining the fuze in unarmed condition until the projectile is free of the gun barrel and in ight toward the target. Rough usage in the field and the forces exerted on the projectile while in the gun barrel must not fully arm the fuze. In an electrically operated fuze two switches may be provided in the circuit; the rst switch closed by the conditions affecting the projectile immediately following firing of the gun, and the second switch closed when the projectile contacts the target.

It is an object of this invention to provide a fuze arming switch in which all the arming mechanism is located within the projectile.

It is another object of this invention to provide a fuze arming mechanism which returns to unarmed position upon the cessation of any condition tending to partially arm the fuze.

It is a further object of this invention to provide in an electrically detonated fuze an arming switch operable to arm the fuze only in response to both set-back and spin of the projectile.

Still another object of this invention is to provide in an electrically detonated fuze a circuit showing the detonator which is opened only in response to both set-back and spin of the projectile.

Other objects and features of the present invention will appear hereinafter upon consideration of the following detailed description in connection with the accompanying drawings.

In the drawings, wherein similar reference characters denote similar parts:

Fig. l is a detailed cross-sectional view of a fuze arming switch embodying the present invention with certain parts shown in elevation;

Fig. 2 is a detailed cross-sectional view of a fuze arming switch taken along line 2-2 of Fig. 1 with parts thereof shown in plan;

Fig. 3 is a schematic diagram of a circuit employing an arming switch embodying the present invention shown within a fuze housing.

Referring particularly to Figs. 1 and 2, there follows a description of the fuze arming switch, shown generally at A, in unarmed position. A cylindrical housing 1, having an external shorting lug 2 is iilled with an insulating potting resin formed in two elements for ease of assembly; i.e., main insulator 3 and cap insulator 4. At the top end of main insulator 3 there is an annular shoulder 5 on which the turned-in end 6 of the cylindrical housing is seated. The cap insulator 4 has a lower surface 7 in the form of a truncate cone so that the bottom edge 8 of the housing may be crimped over to secure the insulators in assembled position. The main insulator and the cap insulator have bores therein which, when aligned in assembly, form a cylindrical longitudinal chamber 9. One end of the longitudinal chamber ternu- ICC nates at wall portion 11 while the opposite end terminates at wall portion 12. A small-diameter contact bore 13 aligned and communicating with chamber 9 passes en tirely through wall portion 11. A similar contact bore 14 passes entirely through wall portion 12 at the opposite end of the longitudinal chamber. intersecting chamber 9 at a right angle in the main insulator is an escape bore 15. In assembled position the outer end 16 of the escape bore is closed by housing 1. A spring path 17 (see Fig. 2) is also provided in the main insulator at a right angle to the longitudinal chamber and in communication with the escape bore along substantially its whole length. An arcuate spring retainer groove 18 is also provided in the main insulator in communication with the spring path.

Positioned in the contact bores 13 and 14 and having disc-like portions within the chamber 9 at opposite ends thereof, are a pair of metallic elements; an arming contact 21 and a primary contact 22, respectively. Abutting primary contact 22 is a coil spring 23. The coil spring is guided by stern 24 of plunger 25 to seat against shoulder 26 which is located between the stern and head 27 of the plunger. The head 27 is slidable within the longitudinal chamber 9.

The coil spring 23 presses the plunger 25 forwardly into contact with a non-conducting or dielectric spherical member 28. The dielectric member is in turn urged forwardly into engagement with arming contact 21.

In spring retainer groove 18 (see Fig. 2) an anchor portion 31 of leaf spring 32 is secured. Integral with the anchor portion of the spring there is an actuating portion 33 which extends through spring path 17 into escape bore 15 and contacts the head 27 of plunger 25. The anchor portion 31 of the leaf spring is in contact with the housing 1.

Referring now to Fig. 3, the fuze body (F) is shown in outline with an electric detonator D housed therein adjacent a body cavity E for accommodating additional elements of the explosive train. One terminal 34 of detonator D is connected by primary conductor 35 to primary contact 22 of switch A. The second terminal 36 of the detonator is connected to arming contact 21 of switch A through nose switch B and voltage source C. A shorting conductor 37 electrically connects shorting contact 2 of switch A to terminal 36 of detonator D.

The fuze circuit in Fig. 3 is shown in unarmed position with the detonating circuit not only open-circuited at two points (switches A and B), but with a shorting connection across the terminals of the detonator provided at switch A wherein the primary conductor 35 is connected to the shorting conductor 37. When the pro jectile is fired the shorting connection is broken and the primary contact 22 is connected to the arming contact 21 (in a manner to be explained below) and thus to arming conductor 38 leaving the detonator circuit open only at switch B. Switch B is closed upon striking the target and voltage source C is then discharged through the detonator setting oi the explosive train.

The operation of the fuze arming switch A is as follows: In the unarmed position the switch provides a shorting connection across the detonator D as shown in Fig. 3. In this position (referring now to Figs. 1 and 2) conductor 35 is inserted in primary contact 22. The primary contact is electrically connected to the head 27 of the plunger Z5 by coil spring 23. Leaf spring 32 provides electrical connection between head 27 and the housing 1. Shorting lug 2, which is integral with the housing 1, provides electrical connection between. the housing and the shorting conductor 37. It will be noted that in unarmed condition the head 27 and arming contact 21, the latter connected to arming conductor 38, are prevented from coming into contact by spherical dielectric member 28 positioned between them. Upon setback the plunger 25 moves rearwardly toward primary contact 22 further compressing coil spring 23. Dielectric member 28 follows plunger 25 rearwardly bringing it into alignment with escape bore 15. Now the spin of the projectile urges the dielectric member outwardly into the escape bore forcing leaf spring 32 outwardly in an arcuate course along the escape bore and spring path 17. As the rate of acceleration of the projectile decreases the coil spring 23 acting against the plunger exerts sufficient force to move it in a forward direction in the longitudinal chamber 9, now no longer blocked by the dielectric member. The plunger creeps gradually forward until at last it engages arming contact 21. The arming switch is now in armed position with electrical continuity from primary conductor 35 through primary contact 22, coil spring 23, plunger 25, arming contact 21, and arming conductor 38. In this position the shorting connection has been broken, for the dielectric sphere now lies in escape bore 15 between the plunger 25 and the leaf spring 32 (note dotted line showing of Fig. 2).

The coil spring 23 and the plunger 25 may throughout be considered a moveable portion of the primary contact.

This switch can be adjusted to operate on relatively low setback force. but yet it will not operate when the projectile is accidentally dropped because centrifugal force is also required to place the switch in armed condition. Further, the switch will not remain in a partially armed condition when subjected to sudden shock as on dropping, because when the force tending to move the plunger rearwardly ceases, the coil spring will return the plunger to the initial unarmed position.

While a representative embodiment and certain details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit or scope of the invention. It is my purpose to claim all such changes and modications.

We claim:

1. In a fuze arming switch having a conductive housing encasing a generally cylindrical dielectric body, a primary contact, an arming contact, said primary contact moveable relative to said arming contact in an axial bore in said dielectric body, a moveable dielectric element in said axial bore positioned between said primary and said arming contacts in unarmed position to open circuit, an arming circuit, a radial bore in said dielectric body communicating with said axial bore, a spring shorting contact having electrical connection with said housing moveable in said radial bore to engage said primary contact in unarmed position, said dielectric element responsive to setback to move axially in said axial bore into alignment with said radial bore and responsive to spin to move into said radial bore and force said shorting contact outwardly in said radial bore, said dielectric element thus occupying a position between said primary and shorting contacts and permitting said primary Contact to engage said arming contact.

2. In an electrically detonated fuze for a projectile, a detonator having a pair of terminals, a shorting circuit including said detonator, an arming circuit including said detonator, an arming switch connected into said shorting and arming circuits, said arming switch comprising a plunger connected in said arming circuit with one terminal of said detonator, an arming contact connected to a source of electric current, an impact switch and the other of said detonator terminals, said plunger spring-pressed toward said arming contact, a freely moveable dielectric ball positioned between said plunger and said arming contact to maintain said arming circuit open, a spring shorting contact connected to said other terminal of said detonator and in engagement with said plunger in unarmed position to connect the terminals of said detonator to each other, said dielectric ball responsive to set-back and spin upon tiring forced rearwardly to move said plunger and outwardly against said spring shorting contact to occupy a position between said shorting contact and said plunger freeing said plunger to engage said arming contact to arm the projectile, said impact switch being adapted to close upon contact with a target to permit a iiow of electricity in said arming circuit to ignite said detonator.

3. In a projectile with a fuze arming switch, a source of electric current, a detonator having a pair of terminals and capable of being initiated electrically, a moveable primary contact connected to a first terminal of said detonator, an arming contact connected to a second terminal of said detonator, a dielectric ball positioned between said contacts to maintain said fuze in an unarmed position, an arming circuit including said source of electric current, the primary contact, the dielectric ball, the arming contact, and an impact switch, a shorting resilient contact connected to said second terminal of said detonator and to primary contact to complete shorting circuit and maintain fuze in safety position, said dielectric ball responsive to set back and spin upon ring of projectile to move rearwardly and outwardly to a second position between said primary and said shorting contacts permitting the engagement of said primary and arming contacts to arm said fuze, and said impact switch adapted to be closed upon contact with target to complete the arming circuit and ignite the detonator.

4. In an electrically detonated fuze for a projectile, a conductable housing having a dielectric lining, air axial bore within said dielectric lining, a conductable plunger moveable longitudinally within said axial bore, a coiled spring bearing against said plunger and connected to said housing, a leaf spring shorting contact being attached to said housing making contact with said plunger and moveable in a radial direction, a shorting circuit across the terminals of the detonator including the coiled spring, the plunger, the leaf spring and the housing; an arming contact in said axial bore and electrically connected to a source of electric current, an impact switch connected to the arming contact, a iIeely moveable dielectric ball interposed between said arming contact and said plunger, an armed circuit connected to the terminals of the detonator when in safety position including the plunger, the dielectric ball, the arming contact, source of electric current, and the impact switch; said dielectric ball displaced rearwardly and outwardly by set back and spin upon tiring to move the leaf spring shorting member out of contact with the plunger to break the shorting circuit and the plunger moved to the arming contact by the coiled spring, to arm the fuze, and said impact switch adapted to close upon contact with the target to complete the arming circuit and ignite the detonator.

References Cited in the tile of this patent UNITED STATES PATENTS 2,485,817 Dike Oct. 25, 1949 2,545,474 Kurland Mar. 20, 1951 2,712,791 Bleakney July 12, 1955 2,719,486 Plumley et al. Oct. 4, 1955 FOREIGN PATENTS 1,002,833 France Nov. 7, 1951 

